1. Technical Field
This invention relates to a sleep timer for controlling the power state of a device, and more particularly to a module for automatically changing the power state of a variety of devices at a predetermined point in time.
2. Related Art
Audio/visual recording devices may be equipped with a sleep timer. A sleep timer may be a module that is used to power off a device or to set a device into a standby mode at a predetermined point in time. The point in time is set such that a user has most likely finished using the device, such as when the user has fallen asleep. In this way, power consumption can be reduced, saving battery capacity.
Some sleep timers are manually activated by the user by selecting a time interval from a predefined range of values. After the selected time interval expires, the sleep timer will automatically switch off the device.
Other sleep timers may not require a manual activation. These sleep timers always switch off the device after a fixed time interval has elapsed without any user interaction.
Alternatively, a sleep timer may combine a manual or non-manual sleep timer with a so-called auto-mode sleep timer. The auto-mode sleep timer can automatically switch off a device when power is no longer needed, even though a predetermined time interval has not yet elapsed.
While these sleep timers use different ways to switch off the device, their operation does not reflect the individual situation of a user. Even when a user can select the sleep time interval, the user must know in advance the desired time interval before falling asleep. Accordingly, these sleep timers may switch off a device either too early or too late
Therefore, a need exists for a sleep timer for controlling the power state of a device that takes into account the characteristics of a user's individual behaviour.